Concepts presented herein relate to a drive unit that can be installed onto existing boat lifts in place of the normal hand wheel and ratchet drive used for driving a winch for manually lifting the boat lift, with a compact simple drive that utilizes a threaded worm driven a worm gear on a hollow shaft that fits over the existing winch drive shaft. A friction clutch is used to provide a power drive for the winch.
Many boat lifts have been made where large manual wheels operating through a ratchet will drive a lift or winch shaft through a friction drive. The hand wheel normally drives a ratchet that will permit rotational movement in one direction until the ratchet is released, so that the wheel can be turned in angular increments with safety. A manual winch drive is shown in U.S. Pat. No. 5,211,124.
Boats are getting heavier, and the effort needed to raise and lower a boat out of water using a manual drive even when speed reducing drives are used between the manual wheel and the lift cable is becoming excessive. It is desirable to have a motor drive, but many of the existing lifts are not adapted to direct motor drives. A power unit that drives the outer rim of a manual winch wheel is shown in U.S. Pat. No. 4,959,011.
The discussion above below is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.